<quote who="Nick Woolley">
> To clarify: The page that is failing is just a regular php page which
> includes some <li> tags which are printed to the page using php code,
> and for some reason the validator is not seeing them (although they are
> working correctly on the web page and shown correctly in the page
> source).
>
> Because the validator thinks there are no <li> tags within the <ul> tags
> it gives an error.
That very strongly suggests that the PHP is, for some reason, failing to
generate the li elements in response to the validator's request.
You can use the View Source option in the validator to see exactly what is
returned.
--
David Dorward
http://dorward.me.uk/